To judge from literature and verbal statements made in recent years, it is probable that among those who read the title of this paper, a substantial proportion will already hold strong views on the relative merits of the two types of system, that these views will reflect a wide range of incompatible conclusions and that they will not all agree on the precise definitions of the two terms themselves. The terms have not been formally defined which has, of course, contributed to the confusion and this is unfortunate because, in the opinion of the author, the terms do lend themselves to logical definition. Furthermore many of the attributes of the two types of concept do confer obvious penalties or advantages which are not seriously in dispute among the contending parties.